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A continuous pursuit-tracking task is the typical experimental paradigm to investigate implicit motor learning. Implicit motor learning is proven by a greater improvement in tracking of a repeated segment of a target path compared to random segments ( Pew, 1974 ). Recently, doubts about the validity of results obtained with this paradigm have been raised. Improved tracking of a repeated segment might simply be due to the characteristics of that particular segment. In response to these doubts, we seek to improve the continuous tracking task. Therefore, we computed a pool of 37 distinct target segments. Participants (N = 36) practiced the tracking task, each one with a unique repeated segment in the middle and varying outer segments, all taken from the pool of segments. After five practice blocks of 36 trials each, a test block was performed where the repeated middle segment was replaced with a random segment. The tracking performance on the repeated segment was better than on random segments. Furthermore, we assume that learning was implicit, because participants' answers to a posttest interview showed they were largely unaware of a repeated segment within the curves.

Many neurophysiological studies give evidence for a matching system between action observation and imitation. We used functional MRI to investigate the effects of different instructions for observing identical stimuli of whole-body gymnastics movements. The imitative-like observation mode asked normal human participants to observe the sequence containing repetitive parts and to subsequently imagine the observed movements in the first-person perspective. The evaluative observation mode asked the participants to carefully observe and judge movement accuracy and consistency in the repetitive sequence. We hypothesized that the supplementary motor area would be specifically involved in performing the observational tasks. Results indicate that the SMA proper is generally activated during observation of whole-body gymnastic movements and shows pronounced activation in imitative-like observation mode. Pre-SMA activity can be differentially modulated by instructions related to the observation task.